My question is -

What is wrong with your plugs when you take them out?

After how many miles?

In the 50s, my uncle Basil sold Lectra fuel igniters - he drove a red Rambler Metropolitan with his claimed MPG painted on the doors - He coasted down hills which was scary at times!

Champion Copper or Bosch, never used NKG. Basic Copper Core single electrode.
B20, B21, B230 since 1983
Used to get Champ N11YC for the B230 and N9YC for the B21... for a $1.50ea off the shelf at the local parts store. No longer stocked.

I have a habit of pulling spark plugs from junkyard redblocks 76 - 95.

If the spark plugs are in fine fettle:
- ground cathode is good
- center (positive) anode is long (enough) and square at the edge (not rounded)

Bosch Copper
Bosch Copper Super (Made in Brazil in the 1992)
NGK Copper

6 or 7 thermal value for driving habits.

Gap set to minimum in the gap range spec.

I've had platinums and iridiums. A few of the Bosch platinums would lose seal between the metal housing and the ceramic material. Both would occasionally foul and not idle well cold. Yet in all instances CO before the cat was perfect if just every so slightly lean upstream of the cat. Of some how the center anode loses conductivity.

Though that was one the first decade of these offerings. I'll guess they are made better?

Also, with the coppers (NGK or Bosch) emissions and fuel economy were better on a 240 with engine control in fine, fine fettle.

I'd not owned Turbo, just helped others with their factory RWD turbo Volvos.

Oh, permetex nickel anti-seize on them spark plug threads and adjust torque touch for secure fit yet no leak. I get ticked when you find a 'surprise' thread insert improperly secured and is not sealed between the insert and the head material, have to figure out the insert manufacturer, and re-treat the insert. Or the receiving thread in the head gives up the ghost the first time you remove a way over tightened plug.

So, coppers. NGK is probably the better in quality. The Bosch copper may last longer a bit. Maybe not.
--
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Hi John,

Use only copper plugs for the red block. However mine is NA 230F.

Have tried platinums, iridium, 3-electrodes, 4-electrodes. They all run in the engine. All idled ok. No misfire. Some idled so smooth the car doesn't sound like a Volvo : ) but felt something less during part throttle opening and overtaking. Need to floor throttle more. Too smooth a combustion maybe. Only to know whats missing when change back to copper.

Have also tried plug indexing. Now this have some real POSITIVE results. Really smooth idle with that copper oomph acceleration. With NGK coppers being least expensive get 2 to 3 sets at one time and choose to install plugs with gaps open towards the intake port (when tightened properly). Could have tried indexing washers but not too sure about heat release issues when plugs not installed in their full depth. But then I don't know what to do with the leftover plugs. So indexing fell slowly out of use.

Currently using - OE coppers from Volvo store in my town (the OE plugs for NA engine is of different make than for turbo - Champion I think). Adequate for the purpose. The heavy Volvo sometimes being left behind in acceleration in these days of lighter cars with plastic/aluminium engine parts and multi-valve setup. Sedate driving now.

That being said you could try coppers from other makers. In these days of mass manufacturing NGK makes no frills good consistent plugs. So NGK wins hands down. Even Bosch have let their quality down somehow by manufacturing in many countries. Still there's hope for Bosch - just take note where the plugs were made. There is a three digit Bosch country code available on the net. This code is stamped on each Bosch product - choose wisely. Other choice would be Champion.

Hope these may help,
Amarin.

Heck, what’s one more confirmation? NGK copper cores like BP6ES. Don’t use anything with a little pointy center electrode, multiple electrodes, or made out of some exotic metal. Been using them in every Volvo we’ve owned from 1972 to 2005. Just got 90,000 miles out of the last set in our 05 S80. Besides, they practically give them away. Actually the Bosch’s that were mentioned are probably pretty much the same thing.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

Standard NGK

For 15 years, drove a 1984.5 245Ti with B21FT-IBS / AW-71. Served as a family car and three teenagers learned to drive in it. Several coast to coast trips and even a stint in Hawaii. Always used the basic copper core NGK BP6ES or BP7ES depending on how the car was being used.

Never a problem with the NGK plugs. My impression was then and still is, that red blocks do best with the basic copper core plugs.

hi john,
i'm sure you'll have a range of opinions.

anything wrong with oem: bosch 7900(WR7DC)?
do a search in bb?

i use them here in the texas heat. no problems, but i don't have a turbo.

regards,
byron golden
86 245
92 245
94 940

Well I got to ditto the standard NGK plugs. Years ago I tried the platinum plugs and had issues. Just didn't run right. Checked alot of stuff and finally went back to the old NGKs I had sitting on the shelf. Felt a difference. So stuck with the NGKs.
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Post Back. That's whats makes this forum work.

Well, I'll be the first to bite. I don't think you can do better, practically speaking, than standard issue NGK. Back in the early '80's I worked at a Honda shop. The cars had very troublesome carbs which required "on car" cleaning and setting. The float level was set with an external screw - the procedure -- turn the screw to raise the level until the motor flooded and stalled and then turn it back a set amount depending on the model. The motors never failed to restart immediately with NGK plugs.
It always seemed to me that having a flooded a B18/20 with carbs you might as well just pull the Bosch plugs out and replace them--it may take a month of drying out before they'ed be usable again. After switching allegiance to NGK that was no longer an issue. I've used NGKs in my Turbo 240's & 940's, '69 144 w/B20, Alfas and MGs and Turbo Saabs with complete satisfaction.
Concerning your worrying about temperature - I may be wrong about this--but I don't really think the ambient temperature has much to do with plug performance. I live on Long Island where the temp range, typically over a year, ranges from single digits to well into the 90's. I don't change plugs based on the season.
Where temp makes a difference is in the combustion chamber. In my 144 which sometimes sees track duty, meaning full throttle for much of a lap and RPMs into the 6,500-7,000 range, I use the colder of the recommended range.
I have no connection with NGK other than liking the product. -- Dave